rob_sri Posted April 15, 2017 Share Posted April 15, 2017 Hi So I have been told there is a way to wire an abs pump to a 12v source to make it modulate.. but after lots of searching I cannot find how to do it.. I've noticed Chris Wilson mention it's easy to do but nobody has posted up how online from what I can see! I'm having trouble bleeding my brakes properly and they seem very spongy after a couple goes with a one man bleed valve Have recently upgraded fronts to ls400, new braided lines, and master cyl has been rebuilt and bench bled.. car is a 94 NA/T with jspecs and no trac.. it stops okay but the pedal is horrible It seems lots of people have similar issues but have managed to fix it by taking a quick blast getting the abs to fire, rebleed, repeat.. I have a wheel sensor out so cannot activate abs by driving it as others have suggested and being as the wheel speed sensor is discontinued I can't just buy a new one Think there is air trapped in the abs system potentially causing this issue as I don't see where else it could be Any tips or suggestions would be ace.. Quote Link to comment Share on other sites More sharing options...
rob_sri Posted April 16, 2017 Author Share Posted April 16, 2017 Anyone? [emoji24] Quote Link to comment Share on other sites More sharing options...
rider Posted April 17, 2017 Share Posted April 17, 2017 Get yourself a 5m length of clear pipe (so you can tackle any wheel) run from the opened calliper bleed to the reservoir run past the front screen and keep on pumping till you no longer see any air rising in the line. If that doesn't sort it there should be a bleed screw on the ABS pump. Never had any problems myself with air locks using this approach and its a one person approach for those with reluctant helpers at home. Quote Link to comment Share on other sites More sharing options...
Dnk Posted April 17, 2017 Share Posted April 17, 2017 I'd re bleed the system, i don't see anything mentioned about doing anything special to do this. I used a vacuum bleeder when we fitted new front and rear calipers and the pedal was perfect but that was with UK brakes Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 19, 2017 Share Posted April 19, 2017 EXTREMELY rare to need to do this, but just put 12V to the main pump connector, ensuring correct polarity. I would put a 5 Amp fuse in line just in case.... I doubt it will help, I have had to do this very infrequently. The "Special Tool" is nothing special, just a piece of loom with a mating connector for the pump... I can hire you the wife, she's superb at bleeding brakes, just don't ask her to cook you anything... Quote Link to comment Share on other sites More sharing options...
rob_sri Posted April 18, 2018 Author Share Posted April 18, 2018 EXTREMELY rare to need to do this, but just put 12V to the main pump connector, ensuring correct polarity. I would put a 5 Amp fuse in line just in case.... I doubt it will help, I have had to do this very infrequently. The "Special Tool" is nothing special, just a piece of loom with a mating connector for the pump... I can hire you the wife, she's superb at bleeding brakes, just don't ask her to cook you anything... I’ve had all the brakes refurbed, braided lines, new master cyl and master cyl stopper, pad backing plates removed and the pedal feel is still awful!! Bled it with the engine on and a pressure bleeder What connections do you have to connect where for the abs.. it’s the only thing I can think of where Old fluid/air could be trapped I’m at my wits end with it! Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 18, 2018 Share Posted April 18, 2018 You are probably bleeding it too fast, press and release the pedal very slowly, close nipple before releasing pedal and open before pressiong again. the power terminals are the two biggest ones with heavy wires. OBSERVE CORRECT POLARITY!!!!!! But i am 99% sure you won't need the pump running, nor the engine. I'll send the Mrs. round, she's a real bleeder. Quote Link to comment Share on other sites More sharing options...
Dnk Posted April 18, 2018 Share Posted April 18, 2018 Bled mine without the engine running after fitting all new brake lines, brake hoses and calipers using a vacuum bleeder, no issues & got a good pedal in one bleed Quote Link to comment Share on other sites More sharing options...
mattdavies Posted April 18, 2018 Share Posted April 18, 2018 Do they feel spongey-er then last time or is this an effort to sort them out ? I would recommend a brake master cylinder stopper Quote Link to comment Share on other sites More sharing options...
rob_sri Posted April 18, 2018 Author Share Posted April 18, 2018 You are probably bleeding it too fast, press and release the pedal very slowly, close nipple before releasing pedal and open before pressiong again. the power terminals are the two biggest ones with heavy wires. OBSERVE CORRECT POLARITY!!!!!! But i am 99% sure you won't need the pump running, nor the engine. I'll send the Mrs. round, she's a real bleeder. Yeah I’m gonna have another go now using that method Just in case.. Connector looks like this do you remember which is which? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 18, 2018 Share Posted April 18, 2018 I can't remember the colour codes, i just back probed them to see what went live, but i am guessing these instructions will apply, bearing in mind there are various types of ABS units fitted to different years and market Supras... The thing takes quite a lot of current so use decent sized wire and make sound connections or things will get hot fast! http://www.lextreme.com/forums/index.php?threads/bleeding-abs-and-trac-system.9358/ Quote Link to comment Share on other sites More sharing options...
rob_sri Posted April 18, 2018 Author Share Posted April 18, 2018 I can't remember the colour codes, i just back probed them to see what went live, but i am guessing these instructions will apply, bearing in mind there are various types of ABS units fitted to different years and market Supras... The thing takes quite a lot of current so use decent sized wire and make sound connections or things will get hot fast! http://www.lextreme.com/forums/index.php?threads/bleeding-abs-and-trac-system.9358/ Yeah the colours etc are different I think il end up blowing it up if I try which might be needed anyway Pedal feel has been shit since the abs sensor went down and then I changed the lines Il do another two person bleed with my flatmate @mharvey and then see what happens there! I’ve read people reporting that they have had similar issues took it for a drive stamped on the pedal to modulate abs then rebled hence why I have it in my mind that is the issue [emoji23] Failing that I’m gonna delete the abs or borrow your wife chris as she obviously has the touch [emoji23][emoji102] Quote Link to comment Share on other sites More sharing options...
Tommyd16 Posted April 18, 2018 Share Posted April 18, 2018 I thought you just needed the ignition on to prime the abs pump then bleed? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 18, 2018 Share Posted April 18, 2018 If it were not for the braided lines I would suggest hose clamps or even carefully used Mole grips to clamp off a caliper flexi hose one at a time. That isolates each caliper hydraulically and you can see if a caliper, (and which one), has air in it. but braided hoses don't like being crushed fluid tight... Quote Link to comment Share on other sites More sharing options...
rob_sri Posted April 19, 2018 Author Share Posted April 19, 2018 I thought you just needed the ignition on to prime the abs pump then bleed? /QUOTE] That I think was the issue.. as my pump won’t prime as the abs sensor is dead Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
rob_sri Posted April 19, 2018 Author Share Posted April 19, 2018 If it were not for the braided lines I would suggest hose clamps or even carefully used Mole grips to clamp off a caliper flexi hose one at a time. That isolates each caliper hydraulically and you can see if a caliper, (and which one), has air in it. but braided hoses don't like being crushed fluid tight... After a lot of swearing and several litres of brake fluid I have something resembling a shit pedal [emoji23] was getting a pedal and then it was going again.. So inconsistent and randomly chucking bits of air out Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 19, 2018 Share Posted April 19, 2018 I would check that no dirt has gotten into the return port of the brake master cylinder by removing it, stripping it and washing in brake cleaner and blowing out with an air line. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 19, 2018 Share Posted April 19, 2018 That I think was the issue.. as my pump won’t prime as the abs sensor is dead /QUOTE] As the MKIV ABS still works, albeit incorrectly, with a dead ABS sensor I doubt that's the case. Quote Link to comment Share on other sites More sharing options...
Tommyd16 Posted April 19, 2018 Share Posted April 19, 2018 There you go. Should sort you out if still needed Pin 2 is live. 1 is ground Quote Link to comment Share on other sites More sharing options...
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